If you want to keep garbage out of landfills, you have to stop thinking about it as garbage. Instead, think of it as resources. This is how Jack Macy thinks. He developed San Francisco’s trailblazing composting program and is currently Zero Waste Coordinator for the city. Here, he shares the city’s secrets to success.

Most cities send thousands of tons of unwanted flotsam and jetsam to landfills every day. But in San Francisco, garbage is treated like a resource that shouldn't be wasted. And that means formulating a plan to reduce the city's garbage output to zero. Yes, that's right: zero.

The last three years have seen an incredible transformation of New York's streetscape. More than 200 miles of bike lanes have been added, while Times Square and many other formerly car-clogged spaces have been turned into havens for pedestrians.

Today, some people look at the decision to halt the Cincinnati subway in 1925 as fatally short-sighted. "If they had finished this system, we may have actually held on to some of our businesses that have left. Cincinnati downtown may have been a viable institution."